A gas fired water heater typically includes a burner element placed strategically adjacent a surface of the hot water reservoir for imparting heat to the water within the reservoir. Normally after this heat exchange, hot exhaust flue gases from the gas fired hot water heater are vented to the atmosphere through a flue pipe. These flue gases are at elevated temperatures and thus, it is clear that all of the available caloric energy has not been extracted by the water reservoir prior to venting. This inefficiency, of course, results in needlessly higher energy bills for hot water use than would be experienced had there been a more efficient heat extraction initially.
Since most of these hot water tanks were designed and continue to reflect technology at a time when energy was relatively cheap and social consciousness about waste of natural resources was not especially high, a long felt yet heretofore unfulfilled need has existed for a more efficient energy extraction to impart heat to the water in the tank.
The following patents reflect the state of the art of which Applicant is aware insofar as these patents appear germane to the patent process:
______________________________________ 273,169 Segal 1883 1,226,516 Hill 1917 2,521,462 Kinzelmann 1950 4,163,430 Neumann 1979 4,484,564 Erickson 1984 ______________________________________
While all of these known prior art structures recognize the need and desireability for preheating water for the associated energy savings, the instant invention is distinguished over the known prior art not only structurally, lending it to facile retrofitting on existing systems, but also in the magnitude of the efficiency obtained thereby. The structural distinctions provide benefits unattainable by the prior art and are not rendered obvious wen considering any of the known prior art either singularly or in any conceivable combination. For example, while Hill has a reservoir in the path of exhaust flue gases, there is nothing disclosed which increases residence time of the gas.